Intelligent Control of Vehicle-Based Internal Transport Systems

Publication

Publication

Intelligente besturing van interne voertuigtransportsystemen

“Intelligent control of vehicle-based internal transport (VBIT) systems” copes with real-time dispatching and scheduling of internal-transport vehicles, such as forklifts and guided vehicles. VBIT systems can be found in warehouses, distribution centers, manufacturing plants, airport and transshipment terminals. Using simulation of two realworld
environments, dispatching rules described in literature and
several newly introduced rules are compared on performance. The
performance evaluation suggests that in environments where queue
space is not a restriction, distance-based dispatching rules such as shortest-travel-distance-first outperform time-based dispatching rules such as modified-first-come-first-served and using load prearrival information has a significant positive impact on reducing the average load waiting time. Experimental results also reveal that multi-attribute dispatching rules combining distance and time aspects
of vehicles and loads are robust to variations in working conditions.
In addition, multi-attribute rules which take vehicle empty travel
distance and vehicle requirement at a station into account perform
very well in heavy-traffic VBIT systems such as baggage handling
systems. Besides dispatching rules, the potential contribution of dynamic
vehicle scheduling for VBIT systems is investigated. Experiments using simulation in combination with optimization show that when sufficient pre-arrival information is available a dynamic scheduling approach outperforms the dispatching approach. This thesis also evaluates the impact of guide-path layout, load arrival rate and variance, and the amount of load pre-arrival information on different vehicle control approaches (scheduling and dispatching). Based on
experimental results, recommendations for selecting appropriate vehicle control approaches for specific situations are presented.